//===--- cuda/dynamic_cuda/cuda.pp ------------------------------- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Implement subset of cuda api by calling into cuda library via dlopen
// Does the dlopen/dlsym calls as part of the call to cuInit
//
//===----------------------------------------------------------------------===//

#include "llvm/Support/DynamicLibrary.h"

#include "Debug.h"
#include "cuda.h"
#include "dlwrap.h"

#include <memory>
#include <string>
#include <unordered_map>

DLWRAP_INITIALIZE()

DLWRAP_INTERNAL(cuInit, 1)

DLWRAP(cuCtxGetDevice, 1)
DLWRAP(cuDeviceGet, 2)
DLWRAP(cuDeviceGetAttribute, 3)
DLWRAP(cuDeviceGetCount, 1)
DLWRAP(cuFuncGetAttribute, 3)

// Device info
DLWRAP(cuDeviceGetName, 3)
DLWRAP(cuDeviceTotalMem, 2)
DLWRAP(cuDriverGetVersion, 1)

DLWRAP(cuGetErrorString, 2)
DLWRAP(cuLaunchKernel, 11)

DLWRAP(cuMemAlloc, 2)
DLWRAP(cuMemAllocHost, 2)
DLWRAP(cuMemAllocManaged, 3)

DLWRAP(cuMemcpyDtoDAsync, 4)
DLWRAP(cuMemcpyDtoH, 3)
DLWRAP(cuMemcpyDtoHAsync, 4)
DLWRAP(cuMemcpyHtoD, 3)
DLWRAP(cuMemcpyHtoDAsync, 4)

DLWRAP(cuMemFree, 1)
DLWRAP(cuMemFreeHost, 1)
DLWRAP(cuModuleGetFunction, 3)
DLWRAP(cuModuleGetGlobal, 4)

DLWRAP(cuModuleUnload, 1)
DLWRAP(cuStreamCreate, 2)
DLWRAP(cuStreamDestroy, 1)
DLWRAP(cuStreamSynchronize, 1)
DLWRAP(cuStreamQuery, 1)
DLWRAP(cuCtxSetCurrent, 1)
DLWRAP(cuDevicePrimaryCtxRelease, 1)
DLWRAP(cuDevicePrimaryCtxGetState, 3)
DLWRAP(cuDevicePrimaryCtxSetFlags, 2)
DLWRAP(cuDevicePrimaryCtxRetain, 2)
DLWRAP(cuModuleLoadDataEx, 5)

DLWRAP(cuDeviceCanAccessPeer, 3)
DLWRAP(cuCtxEnablePeerAccess, 2)
DLWRAP(cuMemcpyPeerAsync, 6)

DLWRAP(cuCtxGetLimit, 2)
DLWRAP(cuCtxSetLimit, 2)

DLWRAP(cuEventCreate, 2)
DLWRAP(cuEventRecord, 2)
DLWRAP(cuStreamWaitEvent, 3)
DLWRAP(cuEventSynchronize, 1)
DLWRAP(cuEventDestroy, 1)

DLWRAP_FINALIZE()

#ifndef DYNAMIC_CUDA_PATH
#define DYNAMIC_CUDA_PATH "libcuda.so"
#endif

#ifndef TARGET_NAME
#define TARGET_NAME CUDA
#endif
#ifndef DEBUG_PREFIX
#define DEBUG_PREFIX "Target " GETNAME(TARGET_NAME) " RTL"
#endif

static bool checkForCUDA() {
  // return true if dlopen succeeded and all functions found

  // Prefer _v2 versions of functions if found in the library
  std::unordered_map<std::string, const char *> TryFirst = {
      {"cuMemAlloc", "cuMemAlloc_v2"},
      {"cuMemFree", "cuMemFree_v2"},
      {"cuMemcpyDtoH", "cuMemcpyDtoH_v2"},
      {"cuMemcpyHtoD", "cuMemcpyHtoD_v2"},
      {"cuStreamDestroy", "cuStreamDestroy_v2"},
      {"cuModuleGetGlobal", "cuModuleGetGlobal_v2"},
      {"cuMemcpyDtoHAsync", "cuMemcpyDtoHAsync_v2"},
      {"cuMemcpyDtoDAsync", "cuMemcpyDtoDAsync_v2"},
      {"cuMemcpyHtoDAsync", "cuMemcpyHtoDAsync_v2"},
      {"cuDevicePrimaryCtxRelease", "cuDevicePrimaryCtxRelease_v2"},
      {"cuDevicePrimaryCtxSetFlags", "cuDevicePrimaryCtxSetFlags_v2"},
  };

  const char *CudaLib = DYNAMIC_CUDA_PATH;
  std::string ErrMsg;
  auto DynlibHandle = std::make_unique<llvm::sys::DynamicLibrary>(
      llvm::sys::DynamicLibrary::getPermanentLibrary(CudaLib, &ErrMsg));
  if (!DynlibHandle->isValid()) {
    DP("Unable to load library '%s': %s!\n", CudaLib, ErrMsg.c_str());
    return false;
  }

  for (size_t I = 0; I < dlwrap::size(); I++) {
    const char *Sym = dlwrap::symbol(I);

    auto It = TryFirst.find(Sym);
    if (It != TryFirst.end()) {
      const char *First = It->second;
      void *P = DynlibHandle->getAddressOfSymbol(First);
      if (P) {
        DP("Implementing %s with dlsym(%s) -> %p\n", Sym, First, P);
        *dlwrap::pointer(I) = P;
        continue;
      }
    }

    void *P = DynlibHandle->getAddressOfSymbol(Sym);
    if (P == nullptr) {
      DP("Unable to find '%s' in '%s'!\n", Sym, CudaLib);
      return false;
    }
    DP("Implementing %s with dlsym(%s) -> %p\n", Sym, Sym, P);

    *dlwrap::pointer(I) = P;
  }

  return true;
}

CUresult cuInit(unsigned X) {
  // Note: Called exactly once from cuda rtl.cpp in a global constructor so
  // does not need to handle being called repeatedly or concurrently
  if (!checkForCUDA()) {
    return CUDA_ERROR_INVALID_HANDLE;
  }
  return dlwrap_cuInit(X);
}
